Alzheimer’s is frequently misdiagnosed. Patients can often have a false-positive, meaning doctors diagnose them with Alzheimer’s even they don’t actually have the disease. On the other hand, Alzeimer’s is often missed in patients — a false-negative — because the pathology resembles other types of dementia such as frontotemporal dementia (FTD) and dementia with Lewy bodies (DLB).

Many studies have shown that the only way to correctly diagnose Alzheimer’s is by using an autopsy-based neuropathologic diagnosis rather than clinical criteria. Current estimates of the true positive rate (sensitivity) is 71 to 87 percent, while the true negative rate (specificity) is 44 to 71 percent.

Psychosis often develops due to brain pathology in neurodegenerative diseases. It can also affect diagnosis rates in Alzheimer’s patients, the actual impact is unclear. Given that a misdiagnosis of Alzheimer’s can have significant implications for clinical care, Canadian researchers set out to determine the rates of misdiagnosis in Alzheimer’s patients with and without psychotic features, using data from the Seattle-based National Alzheimer’s Coordinating Center (NACC) database.

They found that 76 percent of all patients had received a correct Alzheimer’s diagnosis, while 11.9 percent got a false-negative diagnosis and 12.1 percent a false-positive diagnosis of Alzheimer’s.

Then, researchers categorized patients by their psychosis status, using responses to questions about delusions and hallucinations on the Neuropsychiatric Inventory Questionnaire (NPI-Q), which were completed by a study informant.

Their analysis showed that psychotic patients had a higher rate of false-negative diagnosis than did non-psychotic patients as well as a lower rate of false-positive diagnosis. In short, psychotic patients with Alzheimer’s were more likely to have a missed diagnosis of Alzheimer’s but less likely to be falsely diagnosed with the disease.

Interestingly, after subcategorization, researchers determined that psychotic patients were fives times as likely to be misdiagnosed with DLB. On the other hand, patients without psychosis were more likely to be falsely diagnosed with Alzheimer’s when the actual diagnosis was vascular pathology leading to dementia.

“Our research demonstrates that in patients with neuropathologically validated diagnosis of AD, those with psychosis are much more likely to be misdiagnosed with other forms of dementia,” researchers concluded, adding that their study has “raised concern that there may be an underappreciation of how common psychotic symptoms are in AD.” They urged that in the presence of psychosis, clinicians should be less hasty to diagnose a patient with DLB.

Disclaimer:

Alzheimer's News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.

Pin It on Pinterest

We use cookies to ensure that we give you the best experience on our website. If you continue to use this site we will assume that you are happy with it. We never use your cookies for creepy ad retargeting that follows you around the web. OkRead more